LED (Light Emitting Diode) is a kind of a semiconductor which uses the principle of emitting light by converting electric energy into light energy and emitting light when an electrical power is applied to the LED. The lighting apparatus, using this kind of LED, is advantageous in that it has a low electrical energy consumption, a high energy efficiency, a long life span and it can produce various colorful lights compared to the existing fluorescent or incandescent lamps. However, the LED lighting device that is currently used, has the problem of generating high heat when it is operated, which must be cooled off effectively.
In the following introduction, the cooling apparatus of the LED lighting devices of the prior art are disclosed, which features the cooling apparatus of the LED lighting device, combined with the mounting plate of the LED lighting device.
In the prior art KR10-1031650, one of the cooling apparatuses for the LED lighting device is disclosed as below.
The FIGS. 1 and 2 illustrate the status of the mounting plate (210) combined with the cooling apparatus (100) of the LED lighting device, according to the above prior art invention.
The cooling apparatus of the LED lighting device (100), in the illustrated prior art, comprises the heat pipe (110), the heat radiation pin (120) and the binding member (130). The heat pipe (110) is mechanically bound at its one end to the mounting plate (210), which is a part of the LED lighting device. The heat pipe is made pipe shaped and made of stainless steel. The heat pipe is usually made of metal with high heat conductivity like copper. However, there is a disadvantage in that the price of copper is expensive. Therefore it is usual practice that stainless steel is substituted for the copper.
In order to cope with the relatively lower heat transfer efficiency of the stainless steel, a different cooling fluid than the cooling fluid used for general heat pipe is used.
The heat radiation pin (120) is equipped at the other end of the heat pipe (110) and is preferable if it is made of material with high heat transfer coefficient like aluminum The heat pipe (110) and the heat radiation pin (120) are combined by way of extending the heat pipe (110) and pressing the radiation pin to tightly adhere to the extended heat pipe. By this way, there are advantages over the other, prior art that the heat transfer efficiency from the heat pipe (110) to the heat radiation pin (120) increases and the interior space of the heat pipe also increases.
However, the LED lighting device, as described above, has a problem in that the heat emitted from LED during the operation is not efficiently radiated, as the heat pipe is connected alongside to the mounting plate (210) and the heat emitted from LED is to be radiated only through the heat radiation pin (120) connected to the heat pipe at its one end. In addition, an additional constitution of the connecting member (130) is required to connect the heat pipe to the mounting plate, which results in its complicated constitution and additional expenses thereof.
Moreover, in one other Laid-open Publication KR10-2008-0071812 A for ‘LED lighting Assembly Equipped with Cooling Apparatus Using Heat Pipe’, is disclosed.
The FIGS. 3 and 4 illustrate the LED lighting assembly equipped with cooling apparatus using the heat pipe of the prior art. The LED lighting assembly (1) equipped with the cooling apparatus using heat pipe, comprises the heat pipe (10), LED combination (20), the radiating unit (30) and electrical connection (40).
The heat pipe (10) plays a role to rapidly transfer the heat generated by the LED (21) of the LED combination (20) to the radiating unit (30). The heat pipe (10), as shown in a cross sectional view in FIG. 4, has its interior space in vacuum condition. And the interior space is filled with a cooling (working) fluid. The heat pipe (10) is cylindrical shaped and has a heat absorption surface (12), a sealing surface (14) and sidewalls (16). The heat absorption surface (12) is the lower-part of the heat absorption cap. The sealing surface (14) refers to the upper side of the sealing cap. And a through-hole (11) is placed between the heat absorption surface (12) and the sealing surface (14). That is, there is a hole formed in the center area of the heat pipe (10) that is completely running through from the lower-part of the heat absorption cap to the upper side of the sealing cap.
The through-hole (11) is formed by the interior tubular member (18). With reference to the FIG. 9 of the laid-open prior art publication, there are sintered works (58, 60) provided respectively to the upper side of the heat absorption cap and to the inner side of the interior tubular member (18). In the meantime, the sintered work (62), sintered with metal powder, is also provided to the inner side (180) of the interior tubular member (18). Here, the inner side (180), of the interior tubular member (18), means the side toward the interior space (100) of the heat pipe between both sides of the interior tubular member (18).
In the conventional prior art, as introduced in the above, the heat pipe (10) is coupled to LED combination (20) by way of the solder. However, this type of cooling system is comparatively quite large and heavy in view of the usual size of the LED lighting device and therefore, is not suitable for the LED lighting device of high illumination.